Project Summary
Social network analysis, which maps and measures relationships between actors in a network, is often used in epidemiology and public health to model disease transmission patterns. Relationships and the networks they form are affected and influenced by surroundings as well as space and distance. The integration of these networks with spatial and environmental factors, however, is a novel direction for health researchers utilizing these methodologies. Our objectives are thus to develop new techniques for spatial-social network analysis within the realm of medical geography and spatial epidemiology in the case of infectious disease, particularly cholera and other diarrheal illness. Considering space in addition to social interaction allows an accurate perspective on disease transmission and may thus contribute to public health initiatives.
Data used in these analyses comes primarily from the Matlab, Bangladesh study area and the Health and Demographic Surveillance System administered there by the International Center for Diarrheal Disease Research, Bangladesh (ICDDR,B). This specific project was originally initiated with the introduction of social networks to a previously conducted study of cholera vaccine efficacy in Bangladesh. Using data from the vaccine trial, which took place between 1984-1988, positive cholera incidence in both placebo recipients and vaccines was measured in relation to vaccinated individuals within household-level social and kinship networks. The effects of these networks were then measured on a neighborhood level as well. Additional work includes the analysis of cholera rates based on rates in socially-related households over a twenty-one year period, sans intervention. In order to integrate spatial analysis, rates based on neighborhood-level incidence were compared, and known and unknown spatial factors controlled for in the models used. Our results overall suggest that environmental factors play a stronger role in cholera occurrence, which is consistent with literature supporting the hypothesis of primary transmission in humans (i.e. through environmental contact with the cholera pathogen).
Our next steps include re-examining the existing data using networks on a smaller scale and refining the spatial methodologies used. These methods will also be applied to diseases and health outcomes beyond cholera, including shigellosis, which we expect to show stronger association with social networks than cholera. Furthermore, a comprehensive review of social-spatial methods used in geography and other fields is in progress.
Project Team Members
Michael Emch
Sophia Giebultowicz
Elisabeth Root
Mohammad Ali
Peter Bearman
Publications
Emch, ME; Root, ED; Giebultowicz, S; Ali, M; Perez-Heydrich, C; Yunus, M. (in press) Integration of spatial and social network analysis in disease transmission studies. Annals of the Association of American Geographers.
Giebultowicz, S; Ali, M; Yunus, M; Emch, M. (2011) A comparison of spatial and social clustering of cholera in Matlab, Bangladesh. Health & Place. 17: 490–497. link to article
Giebultowicz, S, Ali, M, Yunus, M; Emch, M. (2011) The simultaneous effects of spatial and social networks on cholera transmission. Interdisciplinary Perspectives on Infectious Disease. 2011: Article ID 60437. link to article
Ali, M; Emch, M; Yunus, M; Clemens, J. (2009) Modeling spatial heterogeneity of disease risk and evaluation of the impact of vaccination. Vaccine. 27(28): 3724-3729. link to article
Funding
Emch, M.E. (P.I.); Bearman, P.; Ali, M.; Clemens, J. Integration of Spatial and Social Network Analysis in Vaccine Trials. National Institute of Allergies and Infectious Disease, National Institutes of Health, Award #R03-AI076748, $148,000, 2009-11.
Emch, M.E. (P.I.); Root, E.D.; Bearman, P.; Ali, M.; Clemens, J. Spatial and Social Network Analysis in Vaccine Trials. National Science Foundation, Award # BCS-0924479, $300,183, 2009-12.
Collaborating Institutions
International Center for Diarrheal Disease Research, Bangladesh